Photoresist is a type of liquid chemical that is crucial in the manufacture of semiconductors. Used with photolithography techniques, photoresist facilitates patterning and construction of semiconductor devices on a silicon wafer.
In a semiconductor manufacturing process, photoresist primer is uniformly distributed on a wafer surface, then spun off. The primer cleans the wafer and prepares the wafer to readily adhere to photoresist, said photoresist then being uniformly distributed on the wafer. Then a pattern is flashed onto the photoresist by a specific wavelength light source shining through a mask. The photoresist is reactive to the wavelength, so areas of the photoresist harden, depending on exposure or non-exposure to the light. Subsequent removal of the non-hardened photoresist reveals a pattern of photoresist voids on the wafer that matches the mask that the light shone through. A processing step is then done, the newly formed voids allowing processing only on the exposed silicon. The rest of the photoresist is then stripped off. This pattern and process cycle is repeated with different masks to build desired structures in and on the silicon wafer.
The primer and photoresist step is repeated many times in a semiconductor process, so any small improvements can return big gains in yields, quality, and profits.
Photoresist is expensive, so waste must be minimized. This means that a supply bottle must be drained as much as possible without introducing gas voids into the dispensing system. Gas voids can disable the fluid pump, and bubbles deposited onto the wafer cause spurious voids in the photoresist pattern, which result in a misprocessed wafer.
Particles and foreign elements deposited onto the wafer can also cause mispatterning, so a photoresist dispensing system must also be as clean as possible, and non-reactive with the fluid dispensed.
A wafer damaged because of dispensing malfunction is money lost, so a dispensing system with reliability improvements is favored.
A dispensing system with maintenance improvements, such as quick and inexpensive replacement, is also favored.